Monoclonal antibody therapies are very effective at reducing risk of severe disease and hospitalization from COVID-19, and the Food and Drug Administration (FDA) has extended its emergency use authorization (EUA) to include all children under the age of 12 who test positive for COVID-19, experience mild to moderate symptoms, and are at high risk of developing serious disease.

“In clinical studies of outpatients with COVID-19, a one-time treatment with monoclonal antibodies reduced hospitalization by as much as 70 to 80 percent,” says UNC Health infectious diseases specialist David A. Wohl, MD.

What exactly are monoclonal antibodies and how are they helping those diagnosed or exposed to COVID-19? We asked Dr. Wohl. Here are four things we learned.

1. Monoclonal antibodies are copies of antibodies we know can attack the COVID-19 virus.

When we get an infection, several parts of our immune system fight against the invading pathogen. In the case of COVID-19, one part of the immune response makes a neutralizing antibody, a protein the body makes that latches onto the spike protein that coats the surface of the coronavirus. Once the antibody neutralizes the virus, other parts of the immune system swoop in to dispatch the virus. This general process is part of how people recover from COVID-19.

In the absence of a strong neutralizing antibody, the virus enters the body’s cells and replicates. The more this replication process is allowed to happen unhindered, the sicker an individual will get as the virus spreads within the body.

When the pandemic first began—before vaccines were available—scientists evaluated the antibodies of patients who recovered from COVID-19 to determine which ones best neutralized the virus. They were then able to construct look-alike antibodies in the lab—and now those antibodies can be injected into patients in a one-time treatment.

“We know that some people make incredibly good antibodies to fight the virus, and we’ve been able to copy those antibodies,” Dr. Wohl says.

The antibodies aren’t taken from one person and put in another, like a transfusion. They’re produced in a lab and then given one time as an infusion through an IV to someone who has COVID-19. Studies have also shown that monoclonal antibodies can protect people exposed to COVID-19, such as from an infected household member.

For people with COVID-19, the antibodies get into the circulation before the body can make its own antibodies, which gives a kick-start in fighting the virus. For those exposed but not yet infected, antibodies can be a line of defense that prevents the virus from gaining a foothold in the body.

2. Anyone with COVID-19 at higher risk for progressing to severe disease is eligible for monoclonal antibody treatment.

To receive monoclonal antibodies for treatment, you must have a positive test for COVID-19, have symptoms of COVID-19, and be within 10 days of when your symptoms began.

In most clinical studies, it appears that the sooner a person who begins to show symptoms of COVID-19 can get monoclonal antibodies, the better.

“The value of this may be in the very early days before our body has a chance to make a response, which can take as long as 10 days to two weeks, so if we can jump-start the process, we can start fighting the virus early,” Dr. Wohl says.

In addition, to be eligible to receive monoclonal antibodies you cannot be hospitalized for COVID-19. You must have a higher risk for severe COVID-19 infection due to any of the following:

• Age 65 years or older
• Overweight or obese (may include a body mass index of 25 or greater for adults or the 85th percentile or greater for children)
• Pregnancy
• Diabetes (type 1 or type 2)
• Chronic kidney disease
• Immunosuppressive disease or medication that suppresses the immune system
• Cardiovascular disease (including congenital heart disease) or hypertension (high blood pressure)
• Chronic lung disease such as chronic obstructive pulmonary disease (COPD), moderate to severe asthma, cystic fibrosis or pulmonary hypertension
• Sickle cell disease
• Neurodevelopmental disorders such as cerebral palsy
• Medical-related technological dependence (tracheostomy, gastrostomy or ventilation not related to COVID-19)

Even if you are vaccinated, you can receive monoclonal antibodies if you meet these criteria.

“The FDA has authorized use of monoclonal antibodies in a pretty broad swath of the population,” Dr. Wohl says.

For example, according the CDC, more than 70 percent of the population 20 and older is considered “overweight” and would qualify for monoclonal antibodies.

3. If you have been diagnosed with COVID-19, people in your household may be eligible to receive monoclonal antibodies to prevent infection.

For those exposed to COVID-19 such as by a household member, the criteria for getting a monoclonal antibody treatment include being at higher risk for severe COVID-19, as listed above, plus either not having been fully vaccinated against COVID-19 or having a condition, such as a weakened immune system, that reduces response to the vaccine. Also, the exposure must have been within the previous four days.

“It is a best-kept secret that monoclonal antibodies can be given to people in the same household as a person with COVID-19 to reduce their chance of becoming infected or getting sick,” Dr. Wohl says. “If they do get COVID-19 and have received this treatment, it can actually lower the amount of virus they have and abbreviate their COVID-19 course.”

This is called post-exposure prophylaxis, or PEP, and it’s something that’s used in other diseases such as the flu, hepatitis B and HIV when people are exposed to a virus and receive treatment to prevent them from getting sick or infected.

4. Monoclonal antibodies are not a substitute for a COVID-19 vaccine.

While monoclonal antibodies offer hope to patients at high risk for COVID-19 if they get the virus, a COVID-19 vaccine still offers better protection against hospitalization or death.

Skipping the vaccine because monoclonal antibodies might be available “would be a very foolhardy way to approach this. That would be like saying, ‘I’m not going to use smoke alarms because I have a fire extinguisher,’” Dr. Wohl says. “Forty-six percent of all of the global population has now received at least one dose of a COVID-19 vaccine. When half of humanity has now received the vaccine, I don’t understand how one cannot say the safety of the vaccines is incredible.”

Visit unchealthcare.org/vaccine for the latest information on the COVID-19 vaccines.

This article was originally published Oct. 6, 2021 and updated Dec. 7 and 29, 2021.

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